1. Field of the Invention
This invention relates to a parallel image processing system adapted for multifunctional copying machines, in which image data obtained by an image reading unit and image data provided from external equipment are processed in a parallel manner.
2. Discussion of the Related Art
FIG. 5 shows one example of a conventional digital image processing system.
In the digital copying machine, an IIT (image input terminal) 43 reads an original with a CCD sensor or the like, and converts analog values of the resultant video signal into digital values. The digital signal is converted into binary data, being processed (for instance corrected and edited), by an IPS (image processing system). And an IOT (image output terminal) controls the on/off state of pixels according to the binary data to output a mesh-point image, thereby to reproduce the original's image.
External equipment, such as a PC (personal computer) and a facsimile machine, may be connected to the above-described digital copying machine to share the IOT 46. In this case, as shown in FIG. 5, the IOT 46 is separated from the IIT 43, and a change-over unit 45 is provided therebetween so that the IOT 46 is connected through the change-over unit 45 to the IIT 43, the PC 41 or the facsimile machine 44. Thus, the binary data provided by the PC 41 or the facsimile machine 44 can also be output similarly as in the case of the binary data provided by the IIT 43. In general the PC 41 handles code data, and therefore the PC 41 applies the binary data obtained by bit-mapping the code data to the IOT 46. The facsimile machine 44 supplies the decoded binary data to the IOT 46.
There have been available, as described above, digital image processing systems in which a printer is shared by a digital copying machine, PC, facsimile machine, etc. However, these conventional systems are not so high in productivity, because the elements thereof operate individually and exclusively.
Even in the case of processing both of image data from a scanner and image data from external equipment using a single image bus by giving higher priority to the scanner and taking in the image data from the external equipment during a return period of the scanner, the reading operation from the external apparatus interferes with the operation of the scanner, thereby impairing the copying performance.
To make a single machine available to accommodate a number of inputs, it is conceivable to assign a processing unit to each input. However, such an arrangement runs counter to the efforts in implementing smaller and inexpensive machines.
Particularly, increase in processing speed of copying operations and increasing volume of image data from external equipment due to improvement in the picture quality of images has made it all the more difficult to process the image data from the external equipment during a return period of the scanner.